Circular-type, forced air, forced draft unit heater



Oct. 15, 1957 E. A. NORMAN,JR., ETAL CIRCULAR-TYPE, FORCED AIR, FORCED DRAFT UNIT I'IEATER Filed Aug. 17, 19s:

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1957 IE. A. NORMAN, JR., ETAL ,809,627

CIRCULAR-TYPE, FORCED AIR, FORCED DRAFT UNIT HEATER Filed Aug. 17, 1953 5 Sheetsf-Sheet 2 l I I I I I I ZNVENTORS Fdwczrd A. Norman :72:

Charles 4. Rez'rfieZder/er fiaroZcZ L. Her 59 ATTORNEY fit. 15, 1957 E. A. NORMAN, JR., ETAL CIRCULAR-TYPE, FORCED AIR, FORCED DRAFT UNIT HEATER Filed Aug. '17, 1955 5 Sheets-Sheet 3 IN VENTORS Afar/wen ff):

Edward 1? Cl'iiczrZevs .4. lPez skewer/er ficzraia" Z. Her g BY ATTORNEY United States Patent Ofiice 2,809,627 Patented Oct. 15, 1957 CIRCULAR-TYPE, FORCED AIR, FORCED DRAFT UNIT I-EATER Edward A. Norman, Jr., Charles A. Reichelderfer, and

Harold L. Herzig, Columbus, Ohio, assignors to Norman Products Company, Columbus, Ohio, a corporation of Ohio Application August 17, 1953, Serial No. 374,544

3 Claims. (Cl. 126-110) The present invention is concerned generally with unitary room-heating appliances and, more specifically, with unit heaters of the type adapted for placement in the upper part of a room to be heated thereby, usually adjacent to the room ceiling, and wherein the unit embodies a substantially circular casing from which heated air is discharged circumferentially for downward flow to underlying room areas.

Such a room heater is exemplified in the prior Patent No. 2,519,496 of the applicant E. A. Norman, Jr., and it is a leading object of the present invention to improve the construction and heating characteristics of circular unit heaters of the type set forth in said patent by the provision of a novel heat-exchanger, which is adapted to be arranged within the unit casing and through which high temperature burner gases are passed under forced draft conditions, provision being made for producing forced flow of air to be heated, and delivered to room areas, over the exterior surfaces of the heat exchanger, and wherein the construction and arrangement of the heat exchanger is such as to substantially equalize or render more uniform the temperature of the heated air as the latter is discharged from all points around the entire outer circumference of the heater casing.

A circular unit air heater of the type disclosed in the aforesaid patent comprises a heat exchanger composed of a plurality of circularly or arcuately arranged tubes stationarily mounted in the circular outer casing of the heater assembly and through which tubes hot burner gases are passed under forced or induced draft conditions, the room air to be heated being forced over the outer surfaces of said tubes and heated by contact therewith. It has been found in the operation of this type of heater that the inlet portions of the heat-exchanger tubes, that is, the end portions of the tubes into which the combustible mixture of air and fuel gas is introduced and burned, attain, in the operation of the heaters, higher wall temperatures than those which exist at the discharge ends of the tubes, there being a progressively decreasing temperature gradient from the inlet or combustion ends of the tubes to the waste gas outlet or discharge ends thereof. As a result of this decreasing temperature gradient, the room-heating air, which is positively advanced in an equalized flow transversely of the heat-exchanging and combustion tubes at all positions throughout their lengths, likewise has imparted thereto by said tubes a corresponding progressively decreasing temperature. The result of this construction and mode of operation is the delivery of air heated to unequal temperatures to difl erent parts of an associated room.

Accordingly, it is another important object of the invention to provide a circular heat-exchanger for unit heaters of the type under consideration in which improved control in the how of burner gases through circularly arranged passages or chambers thereof is caused to take place, whereby to provide greater uniformity in the total heatreleasing capacity of the heat exchanger 2 when the same is considered in vertical transverse cross section around its entire circumference.

Still another object of the invention is to provide an improved heat-generating and exchanging structure for gas-fired forced air and forced draft unit heaters, wherein said structure is formed to include a primary ringshaped combustion chamber in which is positioned at one side thereof a burner mechanism, the latter embodying an orificed pipe member from which a fluid fuel is released on opposite sides thereof for divided flow around the opposite sides of the combustion chamber.

A further object is to provide a heat exchanging and developing structure for circular gas-fired unit heaters, wherein said structure is composed of a primary ringshaped duct or radiator which provides internally thereof a fuel combustion and gas-conducting chamber, a burner mechanism being disposed within and on one side of the chamber in a manner causing burning fuel, developed by the operation of the burner mechanism, to divide and sweep around opposite sides of the chamber, finding vent from the latter through an escape opening formed in a wall of said chamber on a side thereof diametrically opposite to that occupied by the burner mechanism.

Still a further object is to provide a heat-exchanging structure of the character set forth in the immediately preceding paragraph, and wherein the escape opening, employed for venting combustion gases from the chamber of the primary duct or radiator, communicates with inlet openings for said gases formed in a pair of relatively spaced, horizontally arranged, secondary ducts or radiators, the latter being arranged above and in spaced relation from the lower or primary duct or radiator, said secondary ducts or radiators being formed with gas-discharging outlets in the sides thereof disposed diametrically opposite to the combustion gas inlet openings thereof, and in vertical registry with the position occupied by the burner mechanism in the associated underlying primary duct or radiator, so that combustion gases flowing through said ducts, first, are caused to travel from the centrally situated burner mechanism disposed in the primary duct or radiator, in two arcuately directed opposed streams through the'ring-shaped combustion and heat-transfer chamber of the primary radiator, and, second, upwardly through its escape or venting opening and into the thinner ring-shaped chambers of the secondary radiators, the gases dividing into two streams as they travel through the chambers of the secondary radiators while moving in directions of flow opposite to those which obtain in the primary radiator, but at a higher velocity, whereby to provide a heat-exchanger of circular form which heated air liberated from its outer circumference will possess a substantially uniform temperature for room-heating purposes.

An embodiment of a circular gas-fired unit heater formed in accordance with the present invention is illustrated in the accompanying drawings, wherein:

Fig. 1 is a vertical sectional view taken through the improved unit heater of the present invention;

Fig. 2 is a horizontal sectional view on the line 22 of Fig. 1 and illustrating the construction and arrange ment of one of the secondary radiators and its associated motor-driven draft fan or blower;

Fig. 3 is a similar View taken on the plane indicated by the line 33 of Fig. 1, and. showing in horizontal cross section the construction of the primary radiator and its burner mechanism and the forced air fan;

Fig. 4 is a detail vertical transverse. sectional view taken through the primary radiator and its burner mechanism, the plane of the figure being indicated by the line 4-4 of Fig. 1';

' Fig. 5' is a diagrammatic perspective view of the gas-flow controlling and delivering appliances for supplying fuel gas to the burner mechanism;

Fig. 6 is a diagrammatic view of a modified form of the invention;

Fig. 7 is a like view of a still further modified form.

Referring more parficularly to'the drawings, the unit heater of the present invention comprises an outer circular casing C which in this instance is composed of a bowlshaped base section 1 and a similarly formed but downwardly facing hood-shaped top section 2. The adjacent but relatively spaced edges of these sections are circularly rolled as at 3, providing between them a continuous, circumferentially extending, outlet slot 4 for the peripheral escape or discharge of heated air from the casing. It will be noted that the upper section 2 possesses a greater diameter at the bottom thereof than does the upper edge of drawn preferably from an atmospheric source exterior to the building, or other enclosure, in which the unit heater is mounted, may be drawn into a blower chamber 8 formed internally of said top section.

The blower chamber is defined by a flat, horizontally disposed upper wall 9 which engages and is secured directly to the under surface of the top wall of the upper casing section 2, the wall 9 being formed With an opening through which the frusto-conical wall 611 projects, as shown in Fig. 1. The blower chamber further includes a convolute, vertically disposed, outer wall 10 which possesses in plan the configuration disclosed in Fig. 2, the chamber 8 further including a horizontal bottom wall 11. Brackets 12 project rigidly at spaced intervals from the outer surface of the wall 10. These brackets include horizontally disposed flanges which are formed with openings for the reception of a plurality of vertically extending casing-suspension bolts 13. The upper ends of these bolts are threaded for the reception of clamping nuts 14, the latter bearing on the upper surfaces of the outwardly projecting flanges of the brackets 12 and the upper surface of the top wall 5 of the upper casing section 2. The extreme upper ends of the bolts 13 are connected by threaded nuts 15 with the lower ends of stationary hanger brackets 16, which are adapted to be connected with a room ceiling or other type of overhead support. The lower ends of the bolts 13 are threaded for reception in openings formed in an arcuate spider 17. The latter carries depending bolts 18 which have their lower ends threaded for the reception of clamping nuts 19 used in holding the base section 1 of the casing in operative relationship with the top section 2.

Fastened to the bottom wall 11 of the blower chamber is the base end of the frame of an electric motor 20, the

latter including an armature 21, which, in the form of the invention illustrated, has its upper end connected with a blower, fan or rotor 22 arranged in the blower chamber 8, while the lower end of the armature is connected with the hub of a fan 23, the latter being rotatably positioned in a room air inlet opening 24 formedaxially in the bottom of the base section 1. When the motor is in active operation, the rotation of its armature shaft 21 causes rotation of the blower 22, causingair, drawn usually from the atmosphere exterior to the building containing the heater, to be advanced under positive flow to the burner mechanism B for fuel combustion purposes, as will be presently explained. Also, the operation of the motor causes rotation, of the fan 23, whereby. air is drawn from the room atmosphere and passes through the inlet 24 forregulated'trave] over the heated exterior'surface 'of an improved heat-exchanger H, hereinafter described in detail, and thereafter redelivered in a heated state to the room atmosphere through the annular outlet slot 4.

The heat exchanger H comprises a horizontally disposed, ring-shaped, primary duct or radiator 25, in which the burner mechanism B 'is mounted. The burner mechanism is disposed on one side of the primary radiator Within the annular combustion and gas-conducting chamber 26 formed therein. Air for combustion purposes is supplied to the burner mechanism by a vertically disposed conduit 27, which at its upper end communicates with the blower chamber 8 and its lower end with the shell 28 of the burner mechanism. V

In this instance the shell 28 is formed with a pair of vertically spaced upper and lower compartments 29 and 30, respectively, the shell extending generally transversely of the chamber 26, These-compartments are provided with inwardly extending and angularly disposed perforated side walls 31, the latter forming on opposite sides of the shell outwardly flaring throats 32. Between the compartment-forming walls of the shell there is positioned a gas-discharging burner tube '33 having rows of gasreleasing orifices 34 disposed on opposite sides thereof. Fuel gas issuing under supply main pressures passes into the throats 32 where the gas combines with combustion air discharged through the perforations in the walls 31, forming highlycombustible mixtures which are immediately ignited and burned in a manner producing two streams of burning combustion gas which flow around the opposite sides of the chamber 26 from the burner B, as shown by the arrows a of Fig. 3.

The combustion gases, during this travel around the lower or primary radiator 25 of the heat exchanger, impart heat to the walls of said radiator, so that room air flowing over the outer surfaces of said walls, by the positive action of the fan 23, is heated thereby and the temperature of the air increased for room delivery.

In order to equalize substantially the temperature of the exchanger heated room air by the time 'it is discharged from the annular slot 4, the present invention employs in the constructionof the heat exchanger one or more secondary radiators. Inthis instance a pair of such secondary radiators have been illustrated and indicated at 35 and 36. The secondary radiators preferably each possess the same diameter as the lower or primary radiator 25 over which they are arranged in spaced relationship. Each of the secondary radiators is substantially thinner in its vertical cross-sectional area thanv the primary radiator, so that the velocity of the gases flowing therethrough will be higher than the gas velocities in the primary radiator.

The secondary radiator 35 communicates with the interior of the primary radiator by means of a short conduit union 37 so that the combustion gases will flow from the primary radiator on the side thereof diametrically opposite to that containing the burner B and will enter the secondary radiator 35 and the radiator 36 through the union 37a which is arranged above and in vertical registry with the union 37. As the combustion gases enter the secondary radiators 35 and 36, the gas streams divide in each and pass around the opposite sides thereof in directions, indicated by the arrows x of Fig. 2, generally opposed to their directions of flow through the primary radiator. Such relatively high velocity flow of the combustion gases through the duct chambers of the secondary radiators imparts heat to the walls thereof and to the room air forced over their outer surfaces by the fan 23. However, it will be noted that the direction of gas flow through the primary radiator is the opposite of that.

tions 37. Likewise, in each of the secondary radiators.

'5 the outer wall temperatures decrease from the connections 37 and 37a to the registering gas outlet connections 38 and 38a, since the direction of combustion gas flow therethrough is generally opposite to that which exists in the primary radiator. Therefore it will be'evident that the areas of higher-temperature of the primary radiator are disposed directly under'the areas of lowest temperature of the secondary radiators. On the other side of the heat exchanger, the area of lower temperature on the 'part oftbeprimaryradiator-is disposed immediately below the area -of-highe-rtemperature of-the-secondary radiators. This thermal balance exists completely around the heat exchanger, so that air advanced by the fan 23 and forced in tubular sheet-like flow patterns over the ,exterior surfaces .of both primary and secondary radiators, will, in general, be heated to about the same temperature at any point in its passage over the heat exchanger. This construction, therefore, provides far greater uniformity in the temperature of the heated air discharged from a circular unit heater than has been heretofore obtained, avoiding specifically the presence of hot and cold areas which have been so objectionable heretofore in the functioning of circular unit heaters.

Fuel gas, under conventional main pressure, is supplied to the burner mechanism B by way of a pipe line 39, Which communicates at one end thereof centrally with the underside of the burner orifice tube 33. The pipe line 39 comprises a plurality of individual pipe members united by unions, elbows and other fittings of standard design, as suggested in Fig. 5. The pipe line may include the conventional, automatically operating, gas-flow controlling valves, such as a diaphragm actuated pressure regulator 39a. It also includes a solenoid actuated shut-off valve 40 for opening and closing the pipe line 39 to gas flow, said valve being disposed on the burner side of the pressure regulator 39a. A safety ignition pilot 41 is provided for producing combustion of fuel from the burner, there being a gas-conducting branch line 42 which leads from the body of the shut-off valve 40 to the pilot 41. A solenoid-actuated control valve 43 is provided in the line 42. Also, the automatic controls preferably include a diaphragm-actuated down draft controller 44, the latter including a small-diametered tube 45 whichleads from the top of the controller casing to the air-supplying conduit 27 for the burner B, and with a second similar tube 46 leading from the outlet stack or ventilator conduit 47 to the under side of the controller casing. The operation of the controller diaphragm in its response to unbalanced pressures on the opposite sides thereof opens and closes an electric circuit 48 in which the solenoid coil of the shut-off valve 40 is arranged. Also, this coil is adapted to be disposed in a second operating circuit in which a conventional room thermostat, not shown, is arranged. By the use of the controller, abnormally high down drafts or pressures in the waste gas outlet conduit 47 arrest gas flow to the burner until the condition is relieved.

In delivering room air to the heat exchanger, it will be noted that such air, through the action of the fan 23, is drawn into the heater casing through the bottom opening 24 thereof. The air is then positively advanced around the sides of the motor and travels upwardly in contact with the inner walls of the lower or primary radiator and the upper or secondary radiators and 36. The air then sweeps outwardly through the horizontal spaces 49 and 49a formed, respectively, between the adjoining upper surfaces of the primary radiator and the lower surfaces of the secondary radiator 35 and between the top surfaces of the radiator 35 and the bottom surfaces of the upper radiator 36. Also, the air passes over the top of the upper radiator 36 and within the hood 2 of the heater casing. After such travel in contact, or in heat-transferring relation, with the outer surfaces of the heat exchanger, the room-heating air sweeps downwardly and laterally outwardly of the heater casing through the circular slot 4, heating-the-roomatmosphere and completing its-functional cycle. As a result'of'the novel arrangement and construction of the heat exchangers and burner mechanism arranged therein, there is obtained from the heater a flow of uniformly heated-air to all portions of a room atmosphere influenced thereby, thereby overcoming one of the outstanding objections hitherto present in the operation-of circular heaters of the type disclosed.

The modified construction shown in Fig. 6 sets forth the use of a separate electric motor 50 fordriving-the blower element 22 instead of utilizingthe :motorl20 "for this purpose. Another variation is to reverse the direction of air flow through the heater with respect to the air flow paths as set forth in the description of sthe preferred operation of .Fig. '1. That is, the blades or-vanes of the rotatable fan 23 may be so formed as to cause room air to be drawn'into the circumferential slot 4 of the heater casing for passage over the heating elements, discharging the resulting heated air in a generallydownward direction through and from the bottom opening ,24 :of the casing.

In Fig. 7, the outlet pipe 52, employed for conducting vitiated burner gases from the radiator or heat-exchanger units to a position of safe atmospheric discharge, is surrounded by a fresh air inlet pipe 6a. In this form of our invention, the central top opening 6 is eliminated and fresh air is drawn from any suitable source and delivered by the outer concentric pipe 6a to the fuel burners. Air so delivered to the burners for combustion-promoting purposes may be under natural draft flow or may be forced by a fan or blower.

Other variations are, of course, possible and we reserve the right to employ the same whenever practical conditions indicate the desirability of their adoption for use.

We claim:

1. A gas fired, forced air unit heater comprising an outer casing formed in the bottom thereof with an axially located room air inlet and peripherally thereof with annular outlet means for the discharge of heated air; a primary hollow ring-shaped radiator mounted horizontally in said casing in spaced relation to the walls thereof and defining an internal, annular combustion chamber; a secondary, hollow, ring-shaped radiator mounted in said casing in a generally horizontal plane above and in spaced relation to said primary radiator, said secondary radiator having approximately the same diameter as said primary radiator but having a relatively reduced cross-sectional thickness; gaseous fuel burner means positioned within the combustion chamber of said primary radiator at one side thereof and operable to project flames in two separate arcuate paths through the combustion chamber of said primary radiator; first vertically disposed passage means connecting said combustion chamber with the interior of said secondary radiator for transferring combustion gases from said combustion chamber to the interior of said secondary radiator, said first passage means being disposed at a position substantially diametrically opposite the position of said burner means, said secondary radiator being formed with at least one combustion gas outlet disposed in substantially diametrically opposed relation to said first passage means, whereby to cause combustion gases passing from said primary radiator by way of said first passage means to flow through said secondary radiator toward the outlet of said secondary radiator in directions opposite to the flow of combustion gases through said primary radiator; means forming a remotely extending flue gas outlet positioned above said primary and secondary radiators; second passage means located above said secondary radiator and connecting the gas outlet of said secondary radiator with said remotely extending flue gas outlet; first air-displacing means communicating with the combustion chamber of said primary radiator operable to effect a positive flow of combustion r 7 V gases through the combustion chamber of said primary radiator, through said secondary radiator and out of said flue gas outlet; and second air-displacing means positioned in said casing for effecting positive advance of room air through the room air inlet of said outer casing,

References Cited in the file of this patent UNITED STATES PATENTS Pierce May 20, 1851 Hood July 22, 1884 8 7 Thompson Mar. 27, 1906 Modine Aug. 23, 1932 Bell May 9, 1939 Ryden July 20, 1943 Herbster Dec. 14, 1943 Parrish June 28, 1949 Richards Dec. 27, 1949 Zink May 16, 1950 Norman Aug. 22, 1950 Budlane Mar. 11, 1952 Zink Dec. 9, 1952 Norman et'al. Dec. 21, 1954 FOREIGN PATENTS Switzerland May 1, 1923 

